Bosch 3 pin coilpack pinout

I'm looking for confirmation that the pinout on these babies is as follows :

1 = Trigger

2 = Power &

3 = Gnd

I've spent an hour googling and can only find one mention on an Alfa forum about this. Just in case, the Bosch part# is 0 221 504 456

Thanks, in anticipation.

These are the same as some BMW's, they donot have internal ignitors.

15 = +12V

4a = Secondary ground

1 = Negative

OK - so how are they wired? I get the 12V pin, but I'm more than a little confused on the gnd and secondary gnd. OR . . . is Pin 3 (negative) taken to chassis ground, and Pin 2 (secondary) the low side trigger managed by the ECU ?

There is no "trigger" wire, they do not have built in ignitors. Its just like an old fashion 2 wire coil. Secondary ground goes to the cylinder head or engine block. Negative goes to the ignitor/ignition module/amplifier.